DAYLENGTH
Notice that sunset arrives one to two minutes earlier each day which shortens the length of daylight by 41 minutes plus the 30 minutes contributed by delayed sunrises. Twilight offers minimal extension to the period of daylight this month. Civil twilight provides less than 30 minutes of additional light for outdoor activities at dusk. The skies then darken rapidly through nautical twilight when overhead skies darken and astronomical twilight when the horizon darkens. The reverse progression applies to dawn.

METEOR EVENTS
Be aware of meteor activity overhead and in the northern skies throughout the month, but light from a waxing moon diminishes good viewing for the first half of the month. A waning third quarter moon on October 19 arrives just in time, though, to improve viewing conditions for the Orionid Meteor Shower. The three stars of Orion’s belt should be identifiable in the eastern sky around 10:00pm. The moon will not rise until around 2:00am, so take advantage of the time between midnight and moonrise on the night of October 21/22 when the meteor shower peaks. Up to 30 meteors per hour can be expected under dark skies. Some activity will be visible during the week of October 17-25.
GREAT WORLDWIDE STAR COUNT
Join this international effort, as a citizen scientist, to count the number of stars that can be seen from different localities around the world. Participants in the Northern Hemisphere will estimate the number of stars visible around the constellation Cygnus, the Swan. Observations can be made anytime during October 14-28. Locate Cygnus on this month’s star chart then look for it overhead between 8:00pm and 9:00pm. Darkest skies occur after October 17 when there will be no intereference from the moon. The GWWSC website provides easy-to-use magnitude charts for estimating the number of stars you see. Determine latitude and longitude for your observation site with a GPS unit, the Geocoder link on the GWWSC website, or a topo map. The star count is sponsored by the University Corporation for Atmospheric Research in Boulder, Colorado, to raise awareness of the effect of light pollution on the night sky. Go to their website at http://www.starcount.org/ for directions and a reporting form.

Note: Hold your hand at arm’s length to measure apparent distances in the sky. The width of the little finger approximates 1.5 degrees. Middle, ring, and little finger touching represent about 5 degrees. The width of a fist is about 10 degrees. The fist with the thumb extended at a right angle equals 15 degrees. The hand stretched from thumb to little finger approximates 20-25 degrees. The diameter of both the full moon and the sun spans only 0.5 degree. Adjust for the size of your hand.

To find out when the space shuttle and International Space Station are visible
from your location, go to:
http://spaceflight.nasa.gov/realdata/sightings/index.html and click on Sighting Opportunities.

VISIBLE PLANETS

Jupiter - The super gas giant reigns over the night sky this month. Look for it in the eastern sky around 9:00pm at the beginning of the month. On October 13 the moon passes about five degrees north of the planet. Jupiter reaches opposition on the evening of October 28, when we see its full face reflected back at us at its brightest magnitude. On this day the planet rises as the sun sets and will shine throughout the night as its orbit passes through its nearest point to Earth for the year. (Magnitude -2.9)

Mars - Even though Mars shines as bright as first magnitude stars, it can be difficult to locate in the night sky because the visible disk of the planet is quite small right now. Look for it in the eastern sky as it rises after 2:00am. Mars appears in the center of Cancer at the beginning of the month, halfway between the twin stars of Gemini and the head of Leo. It approaches bright Regulus (Leo) as the month progresses. Find it more easily as the waning moon moves below it on October 20-22. Mars is high in the eastern sky by morning twilight. (Magnitude +1.2)

Note: Apparent magnitude values range from -4 to +6 for most planets and visible stars. The lower the value the brighter the object. A decrease of 1.0 magnitude is 2.5 times brighter.

MAJOR
CONSTELLATIONS this MONTH

Overhead

Aquila
Cygnus
Delphinus
Pegasus
Lyra

Northward

Cassiopeia
Cepheus
Draco
Ursa Major
Ursa Minor

Eastward

Andromeda
Aries
Auriga
Perseus
Pisces
Taurus

Southward

Aquarius
Capricornus
Cetus
Sagittarius

Westward

Corona Borealis
Hercules
Ophiucus

The Summer Triangle (formed by the brightest stars in Lyra, Cygnus, and Aquila) is an asterism (identifiable shape), not a constellation. It now shares the night sky with another asterism—the Great Square, landmark of the autumn sky. The Great Square (formed by the body of Pegasus, the flying horse) is also known as our Window to the Universe. Gaze through the square and look outward, beyond our galaxy, where hundreds of thousands of other galaxies can be seen through large telescopes.

Hold the star chart high above your head and match the compass directions to the direction you are facing. Adjust the star chart by orienting Ursa Major (Big Dipper) to match its position in the sky.

The star chart approximates the sky from astronomical twilight to midnight. As the night and month progresses, the constellations shift toward the northwest. The celestial equator is measured in hours (h).
The ecliptic is measured in degrees.